BZOJ1660: [Usaco2006 Nov]Bad Hair Day 乱发节

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<iostream>
 7 #include<vector>
 8 #include<map>
 9 #include<set>
10 #include<queue>
11 #include<string>
12 #define inf 1000000000
13 #define maxn 80000+100
14 #define maxm 500+100
15 #define eps 1e-10
16 #define ll long long
17 #define pa pair<int,int>
18 using namespace std;
19 inline int read()
20 {
21     int x=0,f=1;char ch=getchar();
22     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
23     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
24     return x*f;
25 }
26 int main()
27 {
28     freopen("input.txt","r",stdin);
29     freopen("output.txt","w",stdout);
30     int n=read(),a[maxn],sta[maxn];
31     for(int i=1;i<=n;i++)a[i]=read();
32     a[n+1]=inf;
33     int top=0;
34     ll ans=0;
35     for(int i=1;i<=n+1;i++)
36     {
37         while(top>0&&a[i]>=a[sta[top]])ans+=i-sta[top--]-1;
38         sta[++top]=i;
39     }
40     printf("%lld\n",ans);
41     return 0;
42 }